Unexpected Decarbonylation of Acylethynylpyrroles under the Action of Cyanomethyl Carbanion: A Robust Access to Ethynylpyrroles.

It has been found that the addition of CHCN anion to the carbonyl group of acylethynylpyrroles, generated from acetonitrile and -BuOK, results in the formation of acetylenic alcohols, which undergo unexpectedly easy (room temperature) decomposition to ethynylpyrroles and cyanomethylphenylketones (-Favorsky reaction). This finding allows a robust synthesis of ethynylpyrroles in up to 95% yields to be developed. Since acylethynylpyrroles became available, the strategy thus found makes ethynylpyrroles more accessible than earlier.

Computational F NMR of trifluoromethyl derivatives of alkenes, pyrimidines, and indenes.

The F NMR chemical shifts of 13 trifluoromethyl derivatives of alkenes, pyrimidines, and indenes were calculated at the DFT level using the BhandHLYP, BHandH, PBE, PBE0, O3LYP, B3LYP, KT2, and KT3 functionals in combination with the pcS-2 basis set. Best result was documented for the BHandHLYP functional: The mean absolute error (MAE) of 0.66 ppm for the scaled values was achieved for the range of about 20 ppm.

Computational studies of [1]benzothieno[2,3-c]naphtho[1,2-f]quinoline.

Early NMR studies of several heterohelicenes containing an annular nitrogen atom and a thiophene ring in their structure suggested the possibility of the lengthening of the carbon-carbon bonds in the interior of the helical turn of the molecule based on the progressive more shielded nature of C resonances toward the center of the helical turn. Computational chemistry capabilities when those NMR studies were performed were primitive in comparison to what is now possible. We now report the optimized geometry and a comparison of the calculated versus observed H and C NMR chemical shift assignments for [1]benzothieno[2,3-c]naphtho[1,2-f]quinoline that confirms these suspicions.

Diastereoselective synthesis of tetrahydropyrrolo[1,2-]oxadiazoles from functionalized Δ-pyrrolines and generated nitrile oxides.

Tetrahydropyrrolo[1,2-]oxadiazoles have been synthesized in good-to-excellent yields the cycloaddition of nitrile oxides ( generated from aldoximes) to readily accessible functionalized Δ-pyrrolines. The reaction proceeds smoothly at room temperature in a two-phase system in the presence of sodium hypochloride as an oxidant to diastereoselectively afford pharmaceutically prospective 1,2,4-oxadiazolines fused with a five-membered ring. The reaction tolerates a broad range of substrates, including those with oxidant-sensitive functional groups and competitive reaction sites.

Phosphine chalcogenides and their derivatives from red phosphorus and functionalized pyridines, imidazoles, pyrazoles and their antimicrobial and cytostatic activity.

Tertiary phosphine oxides, phosphine sulfides, and phosphine selenides containing pyridine, imidazole, and pyrazole groups have been synthesized via the reaction of elemental phosphorus or secondary phosphine oxides with functional pyridines, imidazoles, and pyrazoles. Alkyl tris(2-pyridylethyl)phosphonium iodide and bromide are also obtained by quaternization of the corresponding phosphine. Antimicrobial activity of the synthesized compounds, including nitrogen-containing heterocycles, phosphorus, selenium, and sulfur, with respect to Enterococcus durans, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa microorganisms is evaluated.

Organophosphorus Azoles Incorporating a Tetra-, Penta-, and Hexacoordinated Phosphorus Atom: NMR Spectroscopy and Quantum Chemistry.

The review presents extensive data (from the author's work and the literature) on the stereochemical structure of functionalized organophosphorus azoles (pyrroles, pyrazoles, imidazoles and benzazoles) and related compounds, using multinuclear H, C, P NMR spectroscopy and quantum chemistry. P NMR spectroscopy, combined with high-level quantum-chemical calculations, is the most convenient and reliable approach to studying tetra-, penta-, and hexacoordinated phosphorus atoms of phosphorylated -vinylazoles and evaluating their Z/E isomerization.

Revealing the Reasons for Degeneration of Resonance-Assisted Hydrogen Bond on the Aromatic Platform: Calculations of Ortho-, Meta-, Para-Disubstituted Benzenes, and ()-()-Olefins.

The energies of the O-H∙∙∙O=C intramolecular hydrogen bonds were compared quantitatively for the series of ortho-disubstituted benzenes and -isomers of olefins via a molecular tailoring approach. It was established that the hydrogen bond energy in the former series is significantly less than that in the latter one. The reason for lowering the hydrogen bond energy in the ortho-disubstituted benzenes compared to the -isomers of olefins is the decrease in the π-contribution to the total energy of the complex interaction, in which the hydrogen bond is enhanced by the resonance effect.

Conjugative Stabilization versus Anchimeric Assistance in Carbocations.

In this study, an old concept of anchimeric assistance is viewed from a different angle. Primary cations with two different heteroatomic substituents in the α-position to the cationic carbon atom CHXY−CH2+ (X, Y = Me2N, MeO, Me3Si, Me2P, MeS, MeS, Br) can be stabilized by the migration of either the X or Y group to the cation center. In each case, the migration can be either complete, resulting in the transfer of the migrating group to the adjacent carbon atom and the formation of a secondary carbocation stabilized by the remaining heteroatom, or incomplete, leading to an anchimerically assisted iranium ion.

Acrylamide derivatives: A dynamic nuclear magnetic resonance study.

Substituted acrylamides have found an extensive application in organic and medical chemistry; therefore, it is very important to get insight into their features such as electronic structure, spectral properties, and stereochemical transformations. A correct interpretation of the chemical behavior and biological activity of these heteroatomic systems is impossible without knowledge of the structure of stereodynamic forms and factors determining their relative stability. The structure and peculiarities of stereodynamic behavior of substituted acrylamides and their model compounds were studied by dynamic and multinuclear H, C, and N nuclear magnetic resonance (NMR) spectroscopy in CDCl and DMSO-d solution.

Tritium NMR: A compilation of data and a practical guide.

The present review is focused on experimental methods and structural applications of tritium NMR. It consists of five parts covering accordingly, introduction, brief overview, early (based on the papers appearing before 2000), more recent (based on the papers appeared in the interim of 2000 to 2015), and recent (based on the papers that appeared after 2015) reports. A special interest in this review is focused on practical aspects of tritium NMR spectroscopy, which is thoroughly illustrated by its numerous applications in chemistry and biochemistry.

The Development of Pharmacophore Models for the Search of New Natural Inhibitors of SARS-CoV-2 Spike RBD-ACE2 Binding Interface.

To date, some succeeding variants of SARS-CoV-2 have become more contagious. This virus is known to enter human cells by binding the receptor-binding domain (RBD) of spike protein with the angiotensin-converting enzyme 2 (ACE2), the latter being a membrane protein that regulates the renin-angiotensin system. Since the host cell receptor plays a critical role in viral entry, inhibition of the RBD-ACE2 complex is a promising strategy for preventing COVID-19 infection.

Click Chemistry of Selenium Dihalides: Novel Bicyclic Organoselenium Compounds Based on Selenenylation/Bis-Functionalization Reactions and Evaluation of Glutathione Peroxidase-like Activity.

A number of highly efficient methods for the preparation of novel derivatives of 9-selenabicyclo[3.3.1]nonane in high yields based on selenium dibromide and cis,cis-1,5-cyclooctadiene are reported.

Substituent-Dependent Divergent Synthesis of 2-(3-Amino-2,4-dicyanophenyl)pyrroles, Pyrrolyldienols and 3-Amino-1-acylethylidene-2-cyanopyrrolizines via Reaction of Acylethynylpyrroles with Malononitrile.

An efficient method for the synthesis of pharmaceutically and high-tech prospective 2-(3-amino-2,4-dicyanophenyl)pyrroles (in up to 88% yield) via the reaction of easily available substituted acylethynylpyrroles with malononitrile has been developed. The reaction proceeds in the KOH/MeCN system at 0 °C for 2 h. In the case of 2-acylethynylpyrroles without substituents in the pyrrole ring, the reaction changes direction: instead of the target 2-(3-amino-2,4-dicyanophenyl)pyrroles, the unexpected formation of pyrrolyldienols and products of their intramolecular cyclization, 3-amino-1-acylethylidene-2-cyanopyrrolizines, is observed.

Silatrane-Sulfonamide Hybrids as Promising Antibacterial Agents.

At the A. E. Favorsky Irkutsk Institute of Chemistry, a series of silatrane-sulfonamide hybrids 1a-d and 2a-d was synthesized.

Digitization of the electron shell the localized orbital locator formalism: trends in the size and electronegativity changes of atoms across the periodic table.

The parameters of the (3, -3) critical point in the topology of the localized orbital locator inside the electron shell reveal patterns that make it possible to recognize trends in the size, electronegativity, and ionization energy of atoms in the first four periods of the periodic table.

Arabinogalactan propargyl ethers in the A-coupling reaction with aldehydes and secondary cyclic amines.

A family of novel pharmacologically prospective carbohydrate polymer aminomethylpropargyl derivatives has been synthesized by CuI-catalyzed A-coupling reaction of arabinogalactan propargyl ethers with aldehydes and secondary amines in DMSO at 23-65 °С. The arabinogalactan derivatives bearing phenyl, pyridinе, and furan moieties in combination with piperidyne, pyrrolidyne, morpholine fragments are prepared in up to 95 % yield and 0.3-2.

Four-Component Relativistic Calculations of NMR Shielding Constants of the Transition Metal Complexes-Part 2: Nitrogen-Coordinated Complexes of Cobalt.

Both four-component relativistic and nonrelativistic computations within the GIAO-DFT(PBE0) formalism have been carried out for N and Co NMR shielding constants and chemical shifts of a number of the nitrogen-coordinated complexes of cobalt. It was found that the total values of the calculated nitrogen chemical shifts of considered cobalt complexes span over a range of more than 580 ppm, varying from -452 to +136 ppm. At that, the relativistic corrections to nitrogen shielding constants and chemical shifts were demonstrated to be substantial, changing accordingly from ca.

Recent advances in the liquid-phase Li nuclear magnetic resonance.

The present review is focused on experimental methods and structural applications, including computational aspects, of classical lithium liquid-phase nuclear magnetic resonance (NMR). It consists of four parts covering accordingly a brief overview, early experimental reports (papers of up to about 2015) and more recent (papers appearing in the interim of about 2015 until 2022) results, together with very few but highly prospective computational results.

Effect of colchicine on physiological and biochemical properties of Rhodococcus qingshengii.

The genus Rhodococcus includes polymorphic non-spore-forming gram-positive bacteria belonging to the class Actinobacteria. Together with Mycobacterium and Corynebacterium, Rhodococcus belongs to the Mycolata group. Due to their relatively high growth rate and ability to form biof ilms, Rhodococcus are a convenient model for studying the effect of biologically active compounds on pathogenic Mycolata.

Synthesis of Functional Polyesters -(2,3-epoxypropyl)-4,5,6,7-tetrahydroindole by Anionic Ring-Opening Polymerization.

The functional polyethers of -(2,3-epoxypropyl)-4,5,6,7-tetrahydroindole (in up to 61% yield, M = 8.7-11.7 kDa) and copolymers with ethylene glycol methylglycidyl ether (M = 5.

Heterocyclization of Bis(2-chloroprop-2-en-1-yl)sulfide in Hydrazine Hydrate-KOH: Synthesis of Thiophene and Pyrrole Derivatives.

The article is devoted to heterocyclization of bis(2-chloroprop-2-en-1-yl)sulfide which proceeds in hydrazine hydrate-alkali medium and leads to formation of thiophene and pyrrole derivatives: previously described 4,5,9,10-tetrahydrocycloocta[1,2-c;5,8-c']dithiophene, as well as unknown hydrazone of 5-methylidene-3-methyldihydrothiophen-2-one and 1-amino-2-(propynylsulfanylpropenylsulfanyl)-3,5-dimethylpyrrole. Tentative mechanisms for the formation of the heterocyclic products are discussed. Obtained hydrazone of 5-methylidene-3-methyldihydrothiophen-2-one was used for the synthesis of a range of azine derivatives and in oxidation process with SeO.

New pecJ- ( = 1, 2) Basis Sets for High-Quality Calculations of Indirect Nuclear Spin-Spin Coupling Constants Involving P and Si: The Advanced PEC Method.

In this paper, we presented new -oriented basis sets, pecJ- ( = 1, 2), for phosphorus and silicon, purposed for the high-quality correlated calculations of the NMR spin-spin coupling constants involving these nuclei. The pecJ- basis sets were generated using the modified version of the property-energy consistent (PEC) method, which was introduced in our earlier paper. The modifications applied to the original PEC procedure increased the overall accuracy and robustness of the generated basis sets in relation to the diversity of electronic systems.

Iodine-Mediated Alkoxyselenylation of Alkenes and Dienes with Elemental Selenium.

A one-pot synthesis of linear and cyclic β-alkoxyselenides is developed through the iodine-mediated three-component reaction of elemental selenium with alkenes (dienes) and alcohols. Selenylation of 1,5-hexadiene gives 2,5-di(methoxymethyl)tetrahydroselenophene and 2-methoxy-6-(methoxymethyl)tetrahydro-2-selenopyran via the 5 and 6- cyclization. 1,7-Octadiene affords only linear 1:2 adduct with two terminal double bonds.

Computational NMR of carbohydrates: 1. Glucopyranoses.

A high-level calculation of H and C NMR chemical shifts of α- and β-d-glucopyranoses is carried out at the DFT level with taking into account their conformational composition to reveal the most effective computational protocols. A number of dedicated DFT functionals in combination with Jensen's pcS-n (n = 0-4) family of basis sets were applied to evaluate the most reliable combination. It was found that BHandHLYP/pcS-2 provided the most accurate and reliable computational protocol.